O. Sorlin

Observation of forward neutrons from the break-up of the 11Li neutron halo

Abstract The cross-sections and forward angular distributions of fast neutrons have been studied for the reaction (11Li, 9Li) at 29 MeV/u on targets of Be, Ni and Au. The cross-sections are large and arise essentially from peripheral reactions. The angular distributions of the neutrons are very narrow and indicate the existence of a neutron halo with radius of about 12 fm.

Collapse of the N=28 shell closure in (42)Si.

The energies of the excited states in very neutron-rich (42)Si and (41,43)P have been measured using in-beam gamma-ray spectroscopy from the fragmentation of secondary beams of (42,44)S at 39A MeV. The low 2(+) energy of (42)Si, 770(19) keV, together with the level schemes of (41,43)P, provides evidence for the disappearance of the Z=14 and N=28 spherical shell closures, which is ascribed mainly to the action of proton-neutron tensor forces. New shell model calculations indicate that (42)Si is best described as a well-deformed oblate rotor.

The program LISE: a simulation of fragment separators

This paper describes the program LISE which simulates the operation of fragment separators used to produce radioactive beams via fragmentation. Various aspects of the physical phenomena involved in the production of such radioactive beams are discussed. They include fragmentation cross-sections, energy losses in materials, ionic charge-state distributions, as well as ion optics calculations and acceptance effects. This program is highly user-friendly, and is designed not only to forecast intensities and purities for planning future experiments, but also for beam tuning during experiments where its results can be quickly compared to on-line data. In addition, several general-purpose tools such as a physical parameters calculator, a database of nuclear properties, and relativistic two-body kinematics calculations make it useful even for experiments with stable beams. After a general description of fragment separators, the principles underlying the calculations are presented, followed by a practical description of the program and its features. Finally, a few examples of calculations are compared to on-line data, both qualitatively and quantitatively.

Search for 28O and study of neutron-rich nuclei near the N = 20 shell closure

Abstract A search for 28 O with a 78 AMeV beam of the neutron-rich isotope 36 S has been performed for the first time. Evidence for the unbound character of 28 O was obtained. In the same experiment the half-lives of the very neutron-rich isotopes 27,29 F and 30 Ne were measured and those for 28,29 Ne and 30,31 Na reexamined. The results are compared to shell-model predictions and conclusions drawn regarding the extent of the region of deformation around N = 20.

Two-neutron interferometry as a probe of the nuclear halo

The technique of intensity interferometry is proposed as a probe of the spatial configuration of two-Neutron haloes. After exploring the sensitivity of interferometry to the n-N configuration, it is demonstrated that the application of the standard method for constructing the correlation function is not valid for halo neutrons. A new iterative method is presented and applied to measurements of the dissociation of 6He, 11Li and 14Be. The correlation functions for these systems have thus been extracted for the first time and the corresponding root-Mean-Square n-n separations estimated. The results are in agreement with the predictions of available three-Body models

Identification of the doubly-magic nucleus 100Sn in the reaction 112Sn+natNi at 63 MeV/nucleon

Abstract We report on the production of the doubly-magic nucleus 100 Sn and other proton-rich nuclei in the A ∼ 100 region in the reaction 112 Sn + nat Ni at 63 MeV/nucleon. The experiment was carried out using the high acceptance device SISSI and the Alpha and LISE3 spectrometers at GANIL. The identification of the reaction products ( A , Z and Q ) was made using the measurements of time-of-flight, energy-loss and kinetic energy.

Three-body correlations in Borromean halo nuclei

Three-body correlations in the dissociation of Borromean halo nuclei are explored for the first time using a technique based on intensity interferometry and Dalitz plots. As an example, the breakup of

Experimental evidence for the particle stability of 34Ne and 37Na

^{14}

Identification of μs-isomers produced in the fragmentation of a 112Sn beam

Be into

Beta-decay of 20Mg

^{12}